View Full Version : 99 Pstar 205 LT-R Rough & Surging

05-06-2008, 08:13 AM
This Engine is the MPFI LT-R. First few runs after the winter I can tell that the engine is running rough (mirror shakes on idle, loss of acceleration, and roughness at all power settings). It seems that every once in a while at some mid range power setting, the boat will surge 150 rpm or so, and will completely smooth out like I remember how it used to run. At times the smoothness only lasts a second, and sometimes it seems to last a little longer. I have not done anything yet. I made the following modifications since the last time I ran it: New Stereo, Replaced the Medalion controller on the first run of the year because I left the pitot tubes hooked up (rookie move, new to the midwest), and I moved the electrical sensor on the starter side of the engine block (knock sensor or water temp?) from the block to a tee-fitting so that I could have another block drain. I would appreciate all suggestions.

05-06-2008, 08:59 AM
Did you stabilize the fuel? Sounds like this may just be a case of some old funky fuel. Also generally it is not reccomended to put the knock sensor on a T. When you need to drain the block just take the extra 10 seconds to unscrew the sensor.

And welcome to the site.

05-06-2008, 10:31 AM
Yep, I'd start with the fuel. Could be old, could have condensation in the tank although the fuel water seperator should catch that. Either way thats the most logical place to start.

Next you might want to check the plugs, last season my buddies Bu (i know, I know) was running rough. He was sure it was water in the tank and spent a good month trying to track it down, ended up he had a bad spark plug.

05-06-2008, 01:18 PM
Thanks guys! I did not put stabil in the fuel. I was going to go get plugs but thought I would write a post first. Couple of questions: Why is it not recommended to put the knock sensor on a tee? How exactly does it work? Also, I have not pulled the back plastic cover off of the fuel tank but is there a fuel/water seperator that is completely seperate from the fuel filter mounted next to the engine?